Biomedical subjects
T Xue
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[Antifertility effects of mifepristone and epostane alone and in combination in rats].
A complete interceptive action on pregnancy was shown after ig mifepristone (RU-486) 16 mg.kg-1 or epostane 96 mg.kg-1 on d 10 of pregnancy in rats. The ig ED50 (95% fiducial limits) of RU-486 when given alone and in combination with epostane 12 mg.kg-1 were found to be 7.8 (5.3-10.0) and 2.6 (2.0-3.3) mg.kg-1, respectively (P < 0.05), while those of epostane when given alone and in combination with RU-486 4 mg.kg-1 were 25.5 (19.4-33.6) and 5.6 (4.7-7.4) mg.kg-1, respectively (P < 0.05). An absorption promotor, sodium dodecyl sulfate 24 mg.kg-1 ig, when given in combination with RU-486 8 mg.kg-1 or epostane 24 mg.kg-1, induced complete interceptive action on pregnancy. Levels of plasma progesterone declined significantly when epostane 12 mg.kg-1 was given in combination with RU-486 4 mg.kg-1 as compared with epostane 12 mg.kg-1 alone (P < 0.05). Results showed that drug combination therapy was of benefit both to RU-486 and epostane in their interceptive actions.
Studies on caproic acid fermentation using immobilized cells.
Five carriers were tested for immobilizing caproic acid bacteria. The batch experiment results showed that the calcium alginate was the best one of the five immobilized materials. The characteristics of immobilized caproic acid bacteria cells were evaluated using a standard batch fermentation procedure. In the laboratory-scale experiments, the alginate beads could be maintained at least for 8 months with the yield of the caproic acid level about 11 mg/ml. Under optimum conditions, a maximum yield of caproic acid about 15 mg/ml could be obtained. The observed productive acid rate and its yield of immobilized cells appeared to be greater than that of the corresponding free cells suspension. The cell number per volume of immobilized cells was about ten times that of free cells.
[Pharmacokinetics of epostane in rabbits by HPLC method].
Epostane (Epo), a 3 beta-hydroxysteroid dehydrogenase inhibitor, interrupted pregnancy in rats, rhesus monkeys, and women. Epo concentrations in serum were determined by high performance liquid chromatography (HPLC) at 0.25, 0.5, 1, 2, 4, 8, 16, 32, and 48 h after intragastric Epo 96 mg.kg-1 in rabbits. The concentration-time curve exhibited a 2-compartment open model. The pharmacokinetic parameters were: T1/2ka 0.79 +/- 0.08 h, T1/2 alpha 0.96 +/- 0.08 h, T1/2 beta 6.6 +/- 1.5 h, Vc 14 +/- 3 ml.kg-1, AUC 12.0 +/- 1.9 micrograms.h.ml-1, Tmax 1.8 +/- 0.5 h, Cmax 3.3 +/- 0.5 microgram.ml-1. After rat copora luteum were incubated with hCG 10 IU.ml-1 and Epo 10 or 100 micrograms.ml-1 for 18 and 48 h, luteal cells showed various degrees of degeneration and progesterone production was significantly inhibited.
A novel minor groove binding reagent designed to serve as a "truck" to carry DNA modifying moieties into the major groove.
A site selective DNA minor groove binding tripyrrole peptide has been synthesized as a "truck" to place chemical functionalities into the major groove which are capable of physically modifying DNA, acting as catalysts to hydrolyze DNA, or effectively protecting DNA from various DNA modifying enzymes. The equilibrium dissociation constants for the binding of this peptide to an A3T3 dsDNA binding site have been determined to be nanomolar, and they are compared to the constants for other minor groove binding agents.